Process for refining lead which contains bismuth



Patented a. 18, 1938 V UNITED STATES PATENT OFFICE PROCESS FOR REFININGLEAD'WHICH CON- TAINS BISMUTH Leon Eugene Jollivet, Marseille LEstaque,France, minor to Socit Miniere ct Mtallurgique de Penarroya, Paris,France France, a corporation of No Drawing. Application November 30,1937, Serial No. 177,301. In France January 11, 1937 7 Claims. (01.75-63) duces a partial elimination of bismuth in alloys v containing ahigh contentthereof.

The process which forms the subject of the present invention thusconsists essentially in adding to lead which contains bismuth and whichhas been previously molten, magnesium and potassium in suitablequantities and then allowing the metal bath to cool' to near itstemperature of solidi'lcation.

There is thus formed'a floating crust containing bismuth, magnesium,potassium and lead and which is separated from the bath of metal by anyknown process. I

This floating crust will contain, according to the proportions ofmagnesium and potassium used, the desired part of the bismuth contained,and up to the whole of the bismuth content, the bismuth content of thefused metallic lead being thus able practically to be brought to 0.001%.

After this treatment the lead always contains an excess of magnesium andpotassium from which it can be freed by any known treatment for examplewith chlorine or water vapour.

For putting the process according to the invention into eflect, themagnesium and potassium may be employed in the state of pure metals orof alloys with lead or with other metals, and be added successively orsimulteously to the bath of impure metal to be trea v If desired theproportion of magnesium or potassium utilized maybe diminished and thisdiminution be compensatedby an increase of potassium or magnesium takingcare always to provide a simultaneous or successive addition ofpotassiumand magnesium; one may thus in particular confer upon therefining process additional advantages such for example as minimum costof the reagents employed, greater ease in the treatment of the dresses,etc.

It should be noted that if thelead from which the bismuth isto beremoved contains, besides bismuth, other impurities these may be partlyor wholly contained in the dross with the bismuth.

However as at present there are eflicacious means for the separation ofthese other current impurities from impure lead, it may be moreeconomical to separate from the lead to be treated the greater part ofits other impurities before applying the process of the invention forthe removal of bismuth. I

The-invention is illustrated in the following non-limiting examples.

Example 1 A lead containing 1350 grams of bismuth per metric ton istreated in the fused state with an addition of magnesium equal to 1520grams per metric ton and an addition oil potassium equal to 975 gramsper metric ton. After agitation and cooling to the neighbourhood of thetemperature of solidification, the floating crust is separated. The leadobtained only contains 130 grams of bismuth per metric ton.

v I Example 2 A lead containing 590 grams of bismuth pe metric ton istreated as above with an addition of magnesium equal to 2220 grams permetric ton and an addition of potassium equal to 1240 grams per metricton. After, cooling and separation of the'floating crust the leadobtained only contains'14 grams of bismuth per metric ton.

What I claim is:

'1. Process for refining .lead which contains bismuth, consisting inadding to the lead in the molten state magnesium and potassium, coolingthe metallic bath to the neighbourhood of its solidification point andthen separating therefrom the floating crust in which the bismuth hascollected.

2. Process for refining H lead which contains bismuth, consisting inadding simultaneously to the lead in the molten state magnesium andpotassium, cooling the metallic bath ,to the neighbourhood of itssolidification point and then separating therefrom the floating crust inwhich the bismuth has collected.

3. Process for refining lead which contains bismuth, consisting inadding successively in either sequence to the lead in the molten statemagnesium and potassium, cooling the metallic bath to the neighbourhoodof its soli'dflcation point and then separating therefrom the floatingcrust in which the bismuth has collected. 7

4. Process for refining lead which contains bismuth, consisting inadding to the lead in the molten state magnesium and potassium. in thestate of alloys with lead, cooling the metallic bath to theneighbourhood of its solidification point and then separating therefromthe floating crust in which the bismuth has collected.

5. Process for refining lead which contains bismuth, consisting inadding to the lead in the molten state magnesium and potassium in thestate of alloys with other metals, cooling the metallic bath totheneighbourhood of its solidification point and then separatingtherefrom the floating crust in which the bismuth has collected.

6. Process for refining lead which contains bismuth consisting in addingto the lead in the molten state magnesium and potassium, cooling themetallic bath to the neighbourhood of its 1 solidification point, andthen separating therefrom the floating crustin which the bismuth hascollected, the proportions of magnesium and potassium being coordinatedin the sense that the proportion of one may be varied within certainlimits, this variation being compensated by a corresponding variation inthe opposite sense in the proportion of the other. r

7. Process for refining lead which contains bismuth, consisting inbringing to simultaneous action on the lead in molten state magnesiumand potassium, cooling the metallic bath to the neighbourhood of itssolidification point and then separating therefrom the floating crust inwhich the bismuth has'collected.

LEON EUGENE JOLLIVET.

